title: The effect of static cyclotorsion compensation on refractive and visual outcomes using the Schwind Amaris laser platform for the correction of high astigmatism.
abstract: OBJECTIVE
  To compare the refractive and visual outcomes using the Schwind Amaris excimer laser in patients with high astigmatism (>1D) with and without the static cyclotorsion compensation (SCC) algorithm available with this new laser platform.
  
  
  METHODS
  70 consecutive eyes with ≥1D astigmatism were randomized to treatment with compensation of static cyclotorsion (SCC group- 35 eyes) or not (control group- 35 eyes). A previously validated optimized aspheric ablation algorithm profile was used in every case. All patients underwent LASIK with a microkeratome cut flap.
  
  
  RESULTS
  The SCC and control group did not differ preoperatively, in terms of refractive error, magnitude of astigmatism or in terms of cardinal or oblique astigmatism. Following treatment, average deviation from target was SEq +0.16D, SD±0.52 D, range -0.98 D to +1.71 D in the SCC group compared to +0.46 D, SD±0.61 D, range -0.25 D to +2.35 D in the control group, which was statistically significant (p<0.05). Following treatment, average astigmatism was 0.24 D (SD±0.28 D, range -1.01 D to 0.00 D) in the SCC group compared to 0.46 D (SD±0.42 D, range -1.80 D to 0.00 D) in the control group, which was highly statistically significant (p<0.005). There was no statistical difference in the postoperative uncorrected vision when the aspheric algorithm was used although there was a trend to increased number of lines gained in the SCC group.
  
  
  CONCLUSIONS
  This study shows that static cyclotorsion is accurately compensated for by the Schwind Amaris laser platform. The compensation of static cyclotorsion in patients with moderate astigmatism produces a significant improvement in refractive and astigmatic outcomes than when not compensated.
authors.affiliation: Emmetropia Mediterranean Eye Clinic, Electra Building, Eleftherias Square, Heraklion, Crete, GR 71201, Greece. i.aslanides@emmetropia.gr
authors.forename: Ioannis M
authors.initials: IM
authors.lastname: Aslanides
authors.forename: Georgia
authors.initials: G
authors.lastname: Toliou
authors.forename: Sara
authors.initials: S
authors.lastname: Padroni
authors.forename: Samuel
authors.initials: S
authors.lastname: Arba Mosquera
authors.forename: Sai
authors.initials: S
authors.lastname: Kolli
mesh_terms: D000328:Adult; D000465:Algorithms; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery; D015835:Ocular Motility Disorders / Q000503:physiopathology*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D013524:Surgical Flaps; D014102:Torsion Abnormality / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult